This invention relates to a stator for use in an electromagnetic actuator.
Where an electromagnetic actuator is used to control the operation of, for example a fuel injector, it is known to encapsulate the stator component of the actuator together with the windings associated therewith in a moulded cover of insulating material, the pole faces of the stator component being exposed. In fuel injector applications, the pole faces of the stator are often exposed to fuel at relatively high pressure, and there is a tendency for such fuel to cause the cover to separate from the stator component often resulting in the cover fracturing.
In order to reduce the risk of the cover separating from the stator component, it is known to provide a groove in the outer face of each outer limb of the stator component extending in a direction parallel to the pole faces of the stator component. When the cover is moulded onto the stator component, some of the insulating material of the cover enters the grooves providing a mechanical connection between the cover and the stator component adjacent the pole faces. An arrangement of this type is disclosed in GB 2252675.
The known construction has the disadvantages that the grooves extend across the full width of the stator component thus reducing the magnetic cross-section of the stator both where the mechanical connection is required and where the connection is not required. Further, the ends of the grooves can lead to stress concentrations in the cover material. Such stress concentrations may be acceptable where the cover material is relatively thick.